[in 1955, Doc and Marty rent a tow truck to get the DeLorean out of the mine shaft; Copernicus freezes upon seeing an adjacent graveyard; Marty follows him and is in shock]

Marty: DOC!! DOC!!

Doc: Marty, what is it? You look like you have seen a ghost.

Marty: You're not far off, Doc.

Doc: [sees the tombstone] Great Scott!

Marty: Look at this. "Died September 7th, 1885." That's one week after you wrote the letter! "Erected in memory by his beloved Clara." Who the hell is Clara?

Doc: Marty, please don't stand there!

Marty: Oh! Right. [steps off grave plot] I have to get another picture.

Doc: "Shot in the back by Buford Tannen over a matter of $80." What kind of a future do you call that?!

Doc: Well, good luck. For both our sakes. See you in the future.

Marty: You mean the past.

Doc: Exactly!

Buford: You owe me money, blacksmith.

Doc: How do you figure?

Buford: My horse threw his shoe. And seein' as you was the one who done the shoein', I say that makes you responsible.

Doc: Well, since you never paid me for the job, I say that makes us even!

Buford: Wrong! See, I was on my horse when he threw the shoe and I got thrown off! And that caused me to bust a perfectly good bottle of fine Kentucky red-eye. So, the way I figure it, blacksmith, you owe me $5 for the whiskey and $75 for the horse.

Marty: [under his breath] That's the $80!

Doc: Look! If your horse threw his shoe, bring him back an I'll re-shoe him!

Buford: I done shot that horse!

Doc: Well, that's your problem, Tannen!

Buford: Wrong! That's yours. So, from now on, you better be lookin' behind you when you walk, 'cause one day, you're gonna get a bullet in your back!

[Doc has just saved Marty from being hung by Buford]

Doc: Marty, you're going to have to do something about those clothes. You walk around town dressed like that, you're liable to get shot.

Marty: Or hanged.

Doc: What idiot dressed you in that outfit?

Marty: You did.

Marty: Clayton Ravine was named after a teacher. They say she fell in there a hundred years ago.

Doc: A hundred years ago? That's this year!

Marty: Every kid in school knows that story 'cause we all have teachers we'd like to see fall into the ravine.

Doc: Then she was supposed to go over in that wagon, and... I may have seriously altered history.

Doc: [mildly intoxicated] In the future, we don't need horses. We have motorized carriages called "automobiles." [barflies laugh]

Barfly 3: If everybody's got one of these auto-whats-its, does anybody walk or run any more?

Doc: Of course we run, but for recreation. Fun.

Barfly 3: Run for fun? What the hell kinda fun is that?! [barflies keep laughing]

[Marty and Jennifer are surprised at the Brown family's appearance]

Jennifer: Doctor Brown, I brought this note back from the future and now it's erased.

Doc: Of course it's erased!

Jennifer: But what does that mean?

Doc: It means your future hasn't been written yet. No one's has. Your future is whatever you make it, so make it a good one. Both of you.